But a route leak forces traffic to take a different path, and this potentially results in a pipe being inundated with a significant volume of traffic that cannot be handled by ISPs along that route (or simply a dead-end).
i.e. imagine an ISP in Rio suddenly declaring that they are the best route to reach the networks that contain facebook.com and google.com ... that ISP will DDoS itself or one of their downstream partners. An ISP may not even notice this, but their peers and partners probably will.
A couple of years ago a BGP route leak took out the entire internet for a few hours for people in Australia. They're fairly common unfortunately, but tend to have limited impact and are resolved quite quickly.
People cannot access some internet sites, depending on who they have internet connectivity with.
https://blog.cloudflare.com/route-leak-incident-on-october-2... has more information from a previous time this happened. A key idea is that internet routing depends a lot on trust, and it's possible for a single misconfigured site to cause serious issues across the internet.
This wasn't battle damage, this was operator error. Building a tank to survive a war and building it to work when driven in a ditch are not quite the same.
My connection through a Sprint hotspot is only able to reach www.google.com and plus.google.com (but not news.google.com, reddit, hn, my own website on the other side of the city I'm in, or practically any other website I can think of.)
I got on with tech support this morning and they had no indication that anything was wrong regionally, had me do a factory reset on the device, and verified it was connecting to their network successfully.
So, maybe my issue is resolved, but Sprint is still having peering issues. That is the kind of behavior I would expect to see during an issue like this.
Of course I go into the store and they tell me there have been regional issues for the last two weeks and it's not my device (we can't help you), but everything works fine for me while I'm inside of the store and on the way back. Then 2 miles before back at the office, broken again, call again and phone support guy hasn't heard anything about this Malaysia Telekom debacle or any regional outages in my area. At this point I notice that I can still reach some sites, but most sites are down.
Not completely sure this is related, since I've been having issues since Wednesday afternoon (in fact that would seem to indicate it's unrelated). Also possible I have been having one issue that was fixed by the factory reset, so now I can freely experience the other issue that everyone else around the globe is apparently having today.
I am interested to know from The Expert as well, when Telekom Malaysia fixed their issue (it is actually fixed at the source now, right?) would there be some propagation delay or aftershocks, or should everything just return to normal relatively immediately.
Any networks that both accept the prefixes and see these advertisements as the best path will send their traffic towards the route leaker, who will lack the capacity to handle this traffic, effectively blackholing these routes.
In theory, a large portion of the Internet would have still seen the legitimate routes as better paths, as they would have a shorter AS path (fewer networks in between) than the leaked ones. However, many networks often implement other BGP metrics for traffic engineering, depending on whether they are seeing the routes from a transit/peer/downstream customer, which may override the shortest AS path.
